Volume control



Nov. 24, 1931. N. c. SCHELLENGER' 1,833,041

VOLUME CONTROL Filed March 11, 1929 l-lllllll'lllll-I Patented Nov.

1 UNITED STATES PATENT-'4 OFFICE names 0. scnnmmmnn, or minim-r, mmnnmassronon r cnrcaoo 'mmnonn surrmr comm, orzanxnanr, mmanma conrona'rron or mnmiu v'ommn con-men Application manner 11, 1929. Serial no. mm.

This invention-relates to volume control The present invention relates to volume for radio sets, public address systems, and control devices of this latter type, in which the like, more particularly to a volume contwo or more electrically and mechanically in trol which exercises a control over the cirdependent resistor or potentiometer units 5 cuit at more than one point in the circuit. a are mounted in line and controlled through In ,order to control .the volume of a radio the operation of a single knob or dial.

set it hasbecomethe practice to insert a variable resistor in multiple with one of the be made in any one of several forms, that so Volume control devices of this may windings of a transformer in the radio set. is all of the electrical circuits of the one unit m This control may be exercised at the beginmay be insulated from and independent of ning of the circuit through the set, that is the electrical circuit of theother units,or

adjacent to the antenna or pick-up device a part of these two circuits may be com- I through which radio signals are received moned, and the commoned circuit may be in the set,or in some instances it may be exconnected to the ground.

i ercised at. a'point adjacent to the detector 7 Multiple unit devices of this kind 0 erated by a single shaft are not limited to t e con-' tube ofthe set. I Often times the resistortakes the form of trol of volume in a radio set, a public ada potentiometer or potential divider in that dress system, or the like, as by suitable choice a fixed resistance is connected across the of resistance value and current carrying cawinding of the transformer at the point to pacity the devices may be put to a plurality be controlled and'thejantenna is connected of uses such' as balancing out the hum in an to the variable of the potentiometer, the alternating current power pack, or as a filavolume being controlled by varying the osi- {ment rheostat to control the temperature of tion of this armwith respect to the axe I re-" a; filament of a vacuum tube: V sistance. J My invention, while it is shown appliedto In the modern radio setsin which incor ring a plurality of resistance units coupled tosignals are amplified through a plurality of gethergyis equally applicable to a plurality stages ofradio frequency amphfication beof i'nductanceunits, or a plurality of confore being impressed upon the elements of denser s such as might be .used to control the detector tube, it is often times diificult feed backs or regeneration in a radio reto properly control the volume of the set' by' 'c'e'iver. I the application of a resistor or potentiometer The present invention provides an imat one point in the set; This condition has led provement in supporting and coupling two to the use of theso called gang volume conrheostats or control units so that they may trolin which two or more potentiometers or be operated in unison for joint control of an resistors are inserted in the radio circuit and electric circuit or device. In the manufacoperated to-control the volume at more than him of such combined or combination units one point. For example, the antenna may in quantity, unavoidable slight errors in be coupled to the first tube through a resistalignment of the parts may occur and it is 40 or, and the last radio frequency amplifier the object of my present invention to make may be coupled to the detector through a secprovision for securing a relatively high deond resistor. These two resistors are usugree of accuracy of joint movement and ally connected together mechanicall operated simultaneously by a single ial or conditions of manufacture. 4 knob mounted on the panel. Now in'order to acquaint those skilled in and smoothness of operation under the aforesaid the art with the manner of constructing operatin a device embodyingmy invention I shall escribe in connection with the accompan ing'drawings a specific but optional form the same.

In the drawings: v I Figure 1 is a plan view of an embodiment of the invention;

Figure 2 is a section view of Figure 1, taken along the line 22 looking in the direction of the arrows;

Figure 3 is a cross-section view of Figure 1, out along a middle vertical plane; and

Figure 4 is a circuit diagram illustrating one application of the devices of the invention.

In the embodiment herein illustrated the units 60 and 61 are mounted on a common U- shape frame'member 62 and' controlled by a single knob 87. The unit 60 is mounted on an insulating member 63 which is riveted to the. open end of the U-frame 62, and which serves to insulate the unit 60 from the frame. The insulating plate 63 having the rheostat 60 secured by the clamping nut 86 and hub 84 to its central part and having its ed es secured to the frame 62, acts like a diap ragm to the extent of providing for a limited amount of freedom of self-alignment, axially. and angularly. of the unit 60.. Unit 61 is mounted upon the mid-section of the frame, 62, being insulated therefrom by the washers 7.7, 79, and 80. The unit 61 comprises the tubular sleeve member 75 having a reduced threaded neck extending throu ha hole in the central part of the frame 62. is

neck is threaded to receive the clamping nut 76. The entire device may be mountedby extending the threaded neck of the sleeve member through a hole in a panel or the like and screwin up the nut 76. The shaft.

7 4 has a shou der which bears endwise against the outer end of the threaded neck. On its inner end the shaft 74 has the collar 71' secured thereto as by a setscrew as shown in Figure 2, and between said collar 71 and the sleeve 75 a spring washer 75' is interposed. The unit likewise has its shaft 81 1ournaled in a sleeve member 84' and .re-

. strained against axial dis lacement by a head formed at the left en of the shaft 81 which head has a shoulder restin against the end of the threaded part of t e collar 82 and a spring washer 82' between the collar 82 and the sleeve 84'. A flexible coupling 70 of insulating material connects the shaft 74 of the unit 61 to the shaft 81 of the unit 60. The flexibilit of the coupling 70 and the flexibility of t e mounting of 63 of unit 60 aids in the alignment of the shaft 81' with respect to the shaft 74 to insure smooth easy operation of the device. The resistor unit 61 comprisesthe cuplike metallic body 72 around the outside of which'-.the resistance unit 65 is placed.

The resistance unit 65 comprises the insulator strip 65 around which is woundthe resistance wire 65. The resistance unit 65 is insulated from the frame 72 by the insulating strip 87 which is. placed around the outside edge of the body 72 between it and the resistor. The ends of the resistance unit are connected to terminals. The bushing 75 is provided with a collar which engagesthe edges of an opening in the body 72, and also provided with a thread upon which the nut 76 is threaded to mount the unit upon the support 62. p

The shaft 74 to which the knob 87 is attached is provided with a collar which rests against the end of the bushing 75, and the shank which projects through the opening in the bushin 75 on which shank the collar 71 carrying t e contact member 71 is attached by a set screw or other suitable means. A

spring washer 7 5' is interposed between the inside edge of the bushing 75 and the collar 71 to keep the 'shoulder of the shaft 7 4 firmly against the end of the bushing 75. A slot 13 cut in the end of the collar 71 into which slot the insulator coupling 7 O is fitted. The opposite end of the coupling 70 is fitted into a similar slot in the collar 82 which is mounted on the shaft Slof the unit 60 and which carries the contacting member. of the unit 60. The plate 70 which forms the coupling is notched at its opposite ends to clear the adjacent ends .of the shafts 74 and 81, which ends may vary slightly as to their position with respect to the'hubs or collars 82 and 71'. This plate has integral portions comprising ears extending into narrow parallel sided slots formed in said hubs diametrically disposed on opposite sides of the shaft ends. The plate 70 is further provided with ears extending over the outside surfaces of the hubs 82 and 71 to prevent edgewise diametrical displacement of the plate 70 with respect to either hub. Obviously, the edges of the plate 70 should have suflicient clearance to produce the desired degree of universal motion which it is the object of the plate 70 to accomplish.

- The ears'which extend over the outer surfaces of the hubs do not rest in notches but merely extend axially along the cylindrical surface of the hubs 82 and 71' and are free to play sidewise over such cylindrical surfaces. The use of these latter ears is optional.

By the above arrangement of the plates resting in the notches and held in place against edgewise motion diametrically of the shaft, a limited degree of universal motion is provided. in the coupling between the two shafts to take care of such unavoidable deviations from axial alignment as are encount-.

ered in quantity production. While the coupling is inex ensive and easily constructed for taking up such small lack of alignmentfas occurs in quantity. roduction of the units. It holds the two sha together for rotary or angular motion with very little play and at the sametime permits of the transmission of a considerable to ue. The construction of the unit 60 bein identical with that of 61 need not be descri d in detail at this time.

The-mounting 63, which is preferably made of bakelite or a similar phenol condensation product, is slightly flexi le and permits limited movement of the resistor unit 61 Th6 flexible coupling'70 which fits into the slot 70 in thecollars 71 and 82, ke s the two units together so that when the ob 87 is rotated the contacting member of both units are moved over the'resistance element.

Since the coupling member 70 is an insulator the two units are insulated from each other electrically, and more over are insu lated fromthe frame member 72 which may be mounted upon a conducting. panel. As illustrated, the units 60 and 61 are potentiometers although simple resistance elements mfibe'substituted if desired.

Figure 4, I show one of the many adap- 'tions of myinventionin an electrical circult. For the pur se of illustration, I have shown a portion 0 a radio circuit in which the antenna A is coupled to the first radio frequency transformer T1 by the potentiometer 60. The antenna is connected to the variable I armof the potentiometer and the ends of the resistor are connected to the opposite ends of the .primar winding of transformer. Tl. Si" als' picks up by the antenna are amphfie through the transformers T1, T2, and T3 and the tubes B1, and B2 before being impressed on the grid of the detector tube B3.

The resistor of potentiometer 61 is connected between the plate of the tube B2 and bat-, tery and the rider of 61 is connectedto the one terminal of the primary winding of the transformer T3. I By he arrangement of-the otentiometers '60 and 61, the input and output of the radio frequency amplifier are regulated to, control the volume. This arrangement does notlalter the tunin of the set by adjustment of condensers C2, andO3. Obviously the-variable arms or riders of units and 61 must be insulated from each other and fromound. The units may be inductancesor condensers if desired without departing from the teachin of my invention.

Having t us complied with the statutes and shown and described a preferred embodiment of my invention, what I consider new and desire-to have protected by Letters Patent is pointedout in the appended claims.

What is claimed is:

1. ,In a volume control, a resistance unit comprising a base, 'a resistance element attached to one side of said base and insulated therefrom,.a rider movably engaging said resistance unit, a shaft for moving said rider, a mounting frame from which said base is insulated, a second and similar resistance unit, flexible means for mounting said second I unit. on said frame with its shaftin substantial alignment with the shaft of the first unit,

and a coupling between said shafts through which the rider of said second unit is moved by a movement of the rider of the first.

2. In combination, a resistance Iunit comprising a base, a resistance element attached to one side of saidbase and insulated therefrom, arider movably engaging said resistance unit, a shaft for'movingsaid rider, a

hub for mounting the rider'on the'shaft, a

pair of radial slots in said hub, a mounting frame upon which said unit is mounted and from which, said base i: insulated, a second and similar resistance unit, insulating means for mounting said second unit on said frame with itsresistance element adjacent the-element of the first unit and'with its-shaft in alignment with the shaft of the first unit, and

a coupling of insulating material between said shafts and 'havin tongues engaging said hub slots through whlch the rider of said second unit is moved by a movement of the rider of the first.

3. The combination of a lurality of elec- 9B trical control devices, a sha t in each device,

a mounting therefor, said mountin rigidly supportingone of said'devices an flexibly supporting another with the shafts of the two in substantial alignmentfla coupling between adjacent ends of said shafts, and a knob for simultaneously adjusting said shafts to adjust said devices. I f l 4. In combination, a pair of electrical. circuit controlling devices having operating 106 shafts journaled for rotation and possessing a limited degree of endwise freedom means for mounting said devices with the shafts a d,

jacent to each other and in approximatealignment, contact arms possessing hub mem- 110 bers on said shaft ends, said hub members having substantially diametrically disposed parallel sided slots, and a coupling member comprising a plate provided withpairs of earsat each end, said ears extending into-1'16 said slots and coupling the-contact arms together for rotary motion with a limited d'egree of universal freedom.

. 5. In combinatlon, a pair of rheostats each having a frame member with a circularly dis- '120 posed resistance element, and a shaft member disposed substantially axially with respect to its resistance element and having a radial- 4 1y extending contact'arm possessmgahub member on the shaft, each shaft-being angularly movable for changing location of contact along'the resistance e ement, means for connecting said frame members together with the I shafts substantially in alignment and with the hub members adjacent eachother,

said hub members having parallel sided, diametrically disposed slots, and a flat plate having a pair of spaced ears at each end entering the slots arid forming, in conjunction 5, with the slots, a universal coupling between the'contact arms. a 6.- In combination, a pair of rheostats each having a frame member with 'a'circularly disposed resistance element, and a shaft member disposed substantially axially with respect to its resistance element and having a radially extendin contactarm' possessing a hub member on t e shaft, each shaft being angularly movable for changing location of member, said rheostat having an'operating shaft,'a second rheo'stat having a base and also having a shaft, a thin, flexible plate having its edges only secured to-the frame member and having its central part only connected to the base of thesecond rheostat, the shafts of the two rheostats bein substantially in alignment andhaving their ends adjacent each other, and a coupling having a contact along the resistance element, means with the aforesaid hubs adjacent eac other,

and a flat coupling plate disposed between the ends of the shafts, said plate having a pair a limited freedom for universal motion conmeeting the contact arms on the ends of the 8. In combination, a pair of rheostats comprising bases which are connected to ether, circularly disposed resistance ele ent's said bases subs'tantiall in axial aligmnent, movable contact arms or engagin the rheostats,vsaid contact arms havin hu members which are mounted on the a jacent ends of theshafts, said hub members being provided with substantially diametrically disposed slats, and a coupling plate havin palrs of projections entering said slots an coupling thehubs together for rotary motion, said projections providing'shoulders for limiting radial displacement of the plate with respect to the connected shafts; v

9. In combination, a'pair of rheostats hav ing bases connected together, circularly disposed resistance elementsfon said bases, said rheostats having rotatablymounted shafts provided with contact controlling arms cooperating with. said elements, said arms having hubs provided with narrow, diametrical :Iy disposed slots,;saidf shaits*being 'mounted mounted on said bases, shafts journaled in of ears at each end projectin into the cor- 70 respondingr slots and provi' mg a limlted degree of eedom for universal motion.

In witness whereof, I hereunto subscribe my name this 28th day ofFebrua 1929.

NEWTON-C; SGHELL NGER. 7!;

vnto' 

